1. Field of the Invention
The present invention relates to a multi-site television conference system and a central control apparatus and a conference terminal for use with the multi-site television conference system.
2. Description of the Related Art
Conventionally, a multi-site television conference system presents, to each participant to a television conference, images of participants at the other sites using several techniques. One of the techniques is illustrated in FIG. 10. Referring to FIG. 10, a participant 1A observes images 1B, 1C and 1D at the other sites which are displayed in multi-windows on a single monitor or individually displayed on a plurality of monitors. The technique, however, is disadvantageous in that it cannot be recognized readily who is talking at present and the talking condition is unnatural in that the eyes of the talking person and the eyes of the persons who are listening to the talking person do not coincide with each other.
A solution to the problem is disclosed in Japanese Patent Laid-Open No. Hei 6-351013, in which a plurality of cameras are used. The improved technique is illustrated in FIG. 11. Referring to FIG. 11, cameras 114B, 114C and 114D are arranged at locations in a monitor at which the images 1B, 1C and 1D of the individual participants are displayed. An image picked up by the camera 114B is transmitted to a terminal of the participant of the image 1B, and images picked up by the cameras 114C and 114D are transmitted to the participants of the cameras 1C and 1D. Also the camera for any other participant if it is present is arranged similarly.
With the arrangement described above, for example, if the participant 1A talks to the image 1B, then an image of the participant 1A as viewed from the front is displayed on the image 1B, but images of the participant 1A as viewed from the sides are displayed on the images 1C and 1D. According to the technique, a feeling of presence of each participant in a conference is increased by coincidence of the eyes. However, where n participants at different sites are involved, n-1 cameras must be provided for a terminal of each of the participants. Therefore, as the number of participants increases, it becomes difficult to install a necessary number of cameras.
A further technique which augments the feeling of presence is disclosed in Japanese Patent Laid-Open No. Hei 7-67035 wherein the computer graphics (CG) is utilized to produce and present an image of an imaginary conference space to a participant. According to the technique, images of participants are arranged on the background of a conference room including a table and so forth so that each participant may have a feeling of participation in the conference. This technique adopts also the technique for establishing coincidence of the eyes by means of a plurality of cameras proposed in Japanese Patent Laid-Open No. Hei 6-351013 mentioned hereinabove and similarly has a problem that, as the number of participants increases, it is difficult to install cameras for them.
In this manner, since the conventional television conference systems provide a feeling of presence in a conference to each participant by making the eyes principally of a talking person and one of the other participants, where n participants participate in the conference, n-1 cameras must be installed for each terminal, which makes implementation of the television conference system difficult.